Cathode ray apparatus for character display or conventional cathode ray display



April 13, 1965 3,178,603

H. MOSS CATHODE RAY APPARATUS FOR CHARACTER DISPLAY OR C ONVENTIONALCATHODE RAY DISPLAY Filed Sept. 25, 1958 2 SheetsSheet 1 Poi So INVENTORHilary Moss AT T'OIQ Apl'll 13, 1965 H. Moss 3,178,603

GATHODE RAY APPARATUS FOR CHARACTER DISPLAY OR CONVENTIONAL CATHODE RAYDISPLAY Filed Sept. 25. 1958 2 Sheets-Sheet 2 Potential Source Fig.8

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United States Patent 3,178,603 CATHODE RAY APPARATUS FOR CHARACTERDISPLAY OR CONVENTIONAL CATHODE RAY DISPLAY Hilary Moss, Horseheads,N.Y., assignor to Westinghouse Electric Corporation, East Pittsburgh,Pa., a corporation of Pennsylvania Filed Sept. 25, 1958, Ser. No.763,215 7 Claims. (Cl. 3113- -86) This invention relates to cathode rayapparatus and more specifically to those devices for producingpredetermined character shapes on a display screen.

There are several systems in which a cathode ray tube has been utilizedto develop character shapes without utilizing scanning techniquesapplied to the electron beam to cause the beam to scan or write adesired character.

One such device utilizes an electron beam which is scanned over acharacter shaping member having a plurality of character openingstherein such that the electron beam may be selectively positioned overthe desired character in the beam shaping member. The beam that emergesfrom the beam shaping member has a cross sectional configurationcorresponding to the shape of the aperture or character of the beamshaping member on which the electron beam is positioned. It is necessaryin this type of device that the electron beam after passing through theaperture be returned to the tube axis subsequent to deflection to thedesired position on the fluorescent screen. In this type of system, itis necessary in order to select a particular symbol, not only to deflectthe electron beam prior to the beam shaping member but also return theelectron beam to the tube axis so that the character selection does notcause a shift in the position of the finally displayed character.

Another system utilizes the principle of superimposing an electron beamupon a plurality of character shaped apertures provided in the beamshaping member. The electron beam is of such a cross sectional area asto cover all of the apertures simultaneously. This results in a bundleof differently shaped electron beams emerging from the beam shapingmember. A selection system operates on the plurality of electron beamsemerging from the beam shaping member. The selection system consists ofa deflection system and a disc having a centrally located aperturetherein. The deflection system deflects the plurality of electron beamsso that only one electron beam will pass through the aperture in thedisc member. By proper selection of voltage applied to the deflectionsystem, it is possible to select any one of the character shapedelectron beams.

This invention is more particularly directed to this latter type ofsystem, in which a plurality of electron beams representing all of thecharacters in the beam shaping member is utilized.

It is an object of this invention to provide an improved cathode raytube for producing a display of selected characters.

It is another object to provide an improved cathode ray tube forproducing characters which does not require a system for returning theelectron beam to the axis after selecting the desired electron beam.

It is another object to provide an improved cathode ray tube ofrelatively inexpensive design for providing an improved character shapedbeam selection.

It is another object to provide a shorter cathode ray tube providingcharacter shaped beam display.

It is still another object to provide a cathode ray tube to selectivelydisplay a normal type scan or a character shaped scan.

These and other objects are effected by my invention as will be apparentfrom the following description taken 3,l78,603 Patented Apr. 13, 1965 inaccordance with the accompanying drawing throughout which like referencecharacters indicate like parts, and in which:

FIGURE 1 is a View of a cathode ray tube embodying the teaching of myinvention;

FIGURE 2 is an elevational view of the cathode surface shown in FIG. 1;

FIG. 3 is an elevational view of the first accelerator selectionelectrode shown in FIG. 1;

FIG. 4 is a side view of a modified cathode structure which may beembodied in FIG. 1;

FIG. 5 is an elevational view of the cathode structure shown in FIG. 4;

FIG. 6 is a modified selection electrode which may be utilized in FIG. 1

FIG. 7 illustrates another modified beam scanning member which may beutilized in FIG. 1 and used in conjunction with the selection systemshown in FIG. 6;

FIG. 8 is a view of a cathode ray tube illustrating another modificationof my invention and a system associated therewith;

FIG. 9 is a view of a portion of an electron gun which may be embodiedin FIG. 8; and

FIG. 10 illustrates a modified beam shaping member which is incorporatedin FIG. 8.

Referring in detail to FIGS. 1, 2 and 3, the basic features of myinvention are illustrated incorporated within a cathode ray displaytube. The tube may be of any suitable shape and material including aneck portion 10, a flared portion 12 and a viewing window 14. Theviewing window 14 is of a suitable light transmissive material such asglass. An electron sensitive coating 16 is deposited on the innersurface of the window 14. The coating 16 may be of a suitable phosphormaterial that emits light in response to electron bombardment.Positioned within the neck portion 10 of the tube is an electron gunstructure 20 for generating and forming an electron beam. A suitabledeflection system 18 is also provided for scanning the electron beamover the coating 16 in response to suitable voltages. The deflectionsystem 18 is illustrated as electrostatic but, of course, any othersuitable deflection system may be utilized such as electromagnetic.

The electron gun 20 is illustrated schematically and the electron beamgenerated therein may take many forms and shapes and still fall withinthe teachings of my invention. The electron gun 20 consists of a cathode22, a modulator electrode 26, a first accelerator electrode 30, afocusing anode 34 and a final anode 38. The difference in this electrodesystem over the conventional type electron gun resides in the trioderegion of the gun consisting of the electrodes 22, 26 and 30. Thecathode 22 consists of a tubular portion 19 closed at the end facing thescreen 16 by a member 24. A heater element 21 is 0 provided within thetubular member 19 for providing the necessary heating. The member 24 istransverse to the axis of the neck portion 10. An electron emissivecoating 25 is provided on the outer surface of the member 24. Thecoating 25 is illustrated in FIG. 2 and consists of a plurality ofcharacters formed thereon of electron emissive material such as bariumstrontium carbonate. The cathode 22 may be operated at a potential nearground with the heater 21 connected to a suitable source for providingthe necessary heat to cause the electron emissive coating 25 to emitelectrons.

Positioned adjacent to the electron emissive surface 25 is the modulatoror control grid 26 which is in the form of a disc or plate perpendicularto the axis of the neck portion 10 and substantially parallel to themember 24. The control grid 26 has an aperture 27 centrally locatedwithin the disc. Positioned adjacent to the modulator grid 26 and on theopposite side thereof with respect to the cathode 22 is the firstaccelerator electrode or selection electrode 39. The selection electrodeis comprised of two segments 31 and 32 of electrically conductivematerial and electrically insulated from each other and forming anannularly shaped disc with a centrally located aperture 33 therein. Thestructure of the electrode 30 which is illustrated in FIG. 3 providestwo equally shaped segments 31 and 32 which may be utilized to deflectthe electron beam in a vertical direction. The aperture 33 is alignedwith the axis of the tube and with the aperture 27. The focusing anode34 is a tubular member positioned adjacent the electrode 30. Positionedadjacent to the focusing anode 34 is the final anode member 38 whichconsists of an annular disc shaped member having a centrally locatedaperture 39. The disc also has a flange about its periphery extending ina direction toward the focusing anode 34. The aperture 39 is alsoaligned with the aperture 27.

The electrode system consisting of the cathode 22, the modulatorelectrode 26 and the selection electrode 36 suitably spaced and with theproper voltages applied will project an image of the cathode 22 at theplane of the final anode 33. The spacing and voltages of the system areso chosen that each of the four symbols or characters in the electronemissive coating 25 will fill the aperture 39 in the anode 38. Thedesired symbol may be made to pass through the opening 39 by applying adifference in potential between the segments 31 and 32 of the deflectionelectrode 30. The mean potential of these two segments 31 and 32 ismaintained at the normal first accelerator voltage of about one thousandvolts positive with respect to the potential applied to the cathode 24.The potential difference between the two segments 31 and 32 suppliedfrom a source 37 is varied so that the cone of rays from the triodestructure may be deflected to bring any of the four symbols across theaperture 39 in the anode 38. If the voltage of the focusing anode 34 isdiminished below the normal focusing potential, the result is anappearance of a fairly sharp cathode image which is the object on thescreen. Thus, by proper selection of the voltage applied to the focusinganode 34, the cathode image corresponding in shape to any one of thesymbols of the electron emissive coating 25 may be indi cated on thescreen 16. When the electron beam is focused, that is when the crossoveris the object and is focused on the screen and not the cathode, the spoton the display screen 16 has a structure which is gaussian and which inturn is not dependent on the shape of the emitting cathode area. Thus, atrue circular spot is formed when the tube is properly focused and thisspot serves to scan a raster on the target 16 in the normal manner. Bymeans of periodically injecting gate signals to the electrode 34, it isthus possible to ring the spot with any of the patterns or characters onthe electron emissive coating 25. The character obtained will depend onthe voltage applied across the two segments 31 and 32 of the selectionelectrode 30. Thus, in the structure described one is able to produce asharpe pin point spot in the normal scanning operation as well asproducing an identifying symbol when desired.

The aperture 27 in the modulator electrode 26 in most cases would have adiameter of from 2 to 3 millimeters. Thus, it can be seen that toattempt to deposit electron emissive symbols of such small area on thecathode is an extremely difiicult operation. The structure illustratedin FIGS. 4 and 5 overcomes this objection. The cathode structure 40shown in FIGS. 4 and 5 consists of an electrical conductive member 41which compares to the member 24 in FIG. 1 and on which is deposited acontinuous electron emissive coating 42. A beam forming or shapingmember 44 is provided of a thin disc of nickel or stainless steel inwhich the four symbols to be displayed have been etched-out in a mannershown in FIG. 5 and vertically oriented. The disc 44 is mounted slightlyaway from the electron emissive surface 42 by means of a spacer ring 43of insulating material. The characters or symbols in the disc 44 may beproduced in any suitable manner such as by photographic techniques whichallow extreme precision on such small scale items. The gap between theelectron emissive coating 42 and the beam forming member 44 issubstantially critical and should be about a few thousandths of an inch.The result is that when the cathode is heated, barium from the oxidecoating 42 is distilled onto the edges of the various beam formingapertures in the disc 44 and thus the edges of the beam formingapertures become the primary emitting sources. It has been found thatthis system although not fully understood allows only the edges of theapertures to emit electrons to any extent. Thus, contrary toexpectation, the circle aperture, for example, does not emit over theentire area of the aperture but only about its periphery. This is, ofcourse, necessary in order to obtain a circular character on the displayscreen.

Referring to FIG. 7, a beam forming apertured member 46 is illustratedto show that the structure is not limited to the use of a single linetype orientation of symbols. This, of course, allows one to provide alarger number of characters in the beam forming plate. The beam formingplate 4-6 illustrated in FIG. 7 has a plurality of numerals from i to 9illustrated. In order to provide a two coordinate selection system sothat each symbol can be brought over the mask aperture in the electrode38, the first accelerator or selection electrode must be doubly split asillustrated in FIG. 6. The selection electrode 48 illustrated in FIG. 6consists of four identically shaped segments 49, 5t), 51 and 52insulated from each other and having an aperture 53 therein. Suitabledeflection voltages are applied to the four segments of the electrode 48also so arranged that the mean potential is constant thereby allowingone to select the desired symbol on the member 46.

It has also been noted that it may be desirable, as illustrated in FIG.1, to improve the focusing action of the lens system consisting of theelectrodes 22, 26 and 30 and to equalize the gradients on the cathodesurface to make the cathode surface curved. This will produce a flatterimage field. The cathode surface is curved such as to be concave withrespect to the display screen.

Referring in detail to FIGS. 8 and 9, there is shown a modifiedstructure incorporating my invention. The tube structure is similar tothat described with respect to FIG. 1 and only the electron gun andassociated deflection system is illustrated in FIG. 8. The electron gun60 consists of an indirectly heated cathode 64 having an electronemissive coating 66 with a heater element 62 provided for heating theelectron emissive coating 66. The cathode 64 is shown connected toground potential. Positioned adjacent to the electron emissive coating66 is a beam modulator disc 68 having a centrally located aperture 70.This modulator 68 normally operates at or near cathode potential. Itspotential is controlled by a source 67. Positioned adjacent to themodulator or beam focusing electrode 68 is an accelerator anode 72 towhich a potential of about 200 volts positive with respect to thecathode 64 is supplied from a suitable source 69.

The anode 72 consists of a tubular portion 74 having its axis coincidentwith the electron gun axis. A diaphragm 76 is positioned within thetubular portion 74 transverse to the electron beam axis at the end ofthe tubular member 74 adjacent the beam focusing electrode 68. Thediaphragm 76 has an aperture 78 centrally located therein and alignedwith the aperture in the beam focusing electrode 68. A second diaphragm80 is also provided within the tubular member 74 and spaced from thefirst diaphragm 76. The diaphragm 80 also has an aperture 82 providedtherein and aligned with the apertures '78 and 70. This structureprovides a small triode and serves merely to produce a cone shaped beamof electrons with a half angle of about 20. After passing through theaperture 82 in the electrode 72, the electrons travel in a field freeregion for about 1 to 2 centimeters and are then retarded on approachinga beam forming plate 121 such as is illustrated in FIG. 10. The beamforming plate 121 is operated at a potential of up to about voltspositive with respect to the cathode 64 by means of a source 71. Thebeam forming plate 121 as can be seen in FIG. 10, contains the desiredcharacters etched through the surface. The electron beam is ofsufficient cross sectional area to illuminate the apertures in the beamforming plate 121. The beam forming plate 121 forms in effect thecathode of the main portion of the cathode ray tube.

This virtual cathode forming structure, including the cathode 64,electrode 68, electrode 72 and beam forming plate 121 is positionedwithin a cup-shaped member having aperture 92 provided in the bottomportion of the cup-shaped member. The sides of the cup-shaped member 90are directed away from the screen of the tube and the virtual cathodestructure is positioned therein with the beam forming plate 121 adjacentthe aperture 92. The electrode serves as the control grid of the maingun. Positioned adjacent to the control grid 90 is a beam deflectionelectrode 48 similar to that shown in FIG. 6. The control grid 90operates at a small negative potential with respect to ground suppliedfrom a suitable voltage source 73. An anode 96 is provided adjacent tothe deflection electrode 48 and consists of a tubular member 98 coaxialwith the axis of the electron beam and having a diaphragm 100 at the endof the tubular member 98 remote with respect to the deflection electrode48. The diaphragm 100 also has an aperture 102 centrally locatedtherein. It can be seen that the plurality of electron beams generatedby the beam forming plate 121 which is a virtual cathode is then focusedby the triode system of the virtual cathode containing the desiredsymbols onto the display screen. The anode 96 containing the aperture102 is chosen in size so that only the electron rays from one symbol ofthe beam forming plate 121 can pass through. A selection of the propersymbol is made by varying the potential on the four segments of thesegmented deflection electrode 48. It is found that this selection ordeflection electrode 48 does not cause a change in the position at whichthe symbol is projected on the screen. Selection of this position isdetermined Wholly by the electrostatic or magnetic deflection systemillustrated by the deflection system 18 which provide both the verticaland horizontal deflection.

It has been found that the electrode system consisting of the virtualcathode (formed by the beam forming plate 121), the modulator 90 and thedeflection electrode 48 provides a desirable lens system. The immersionlens projects an inverted cathode image. The focal length of theimmersion lens forming the image depends mainly on the cathode tomodulator grid spacing and, for a given potential applied to the firstaccelerator, on the value of the negative grid bias applied to themodulator grid. When the deflection electrode 48 is split into two orfour segments and a voltage difference is applied between them, it isfound that the full cone of rays from the triode is bodily deflectedabout the fixed apex. It is also found that this deflection isaccompanied by only negligible distortion of the cathode images. It hasbeen found that it is not essential to apply balanced voltages to thesegments of the electrode 48. The acceleration voltage applied to theanode 96 is in no way critical. This voltage, wlnch is supplied from asuitable source 75, is determined almost wholly by the required imagebrilliance. It has been found that a voltage of about ten kilovolts issatisfactory. In order to utilize the higher voltages on the anode 96,it is, of course, necessary to provide a higher voltage on the electrode48. It therefore may be necessary to have selecting voltages applied tothe electrode 43 of greater than 1,000 volts.

The structure illustrated in FIG. 8 has been modified in FIG. 9 toincorporate an amplifying section for each of the segments of thedeflection electrode. In the device shown in FIG. 9, a two segmentedelectrode 30 is illustrated to simplify the drawing. An amplifier isprovided for each segment 31 and 32. In the specific embodiment shown,an emissive coating is shown on the back surface of the cathode support122 while an electron emissive coating 66 is provided on the frontsurface. A common heater, not shown, is provided for both electronemissive coatings 6d and 120. The electron emissive coating 120 iscommon to the two anodes 124 and 12b. The anode 124 is connected to thesegment 31 of the first accelerator 30 and the other anode 126 isconnected to the other segment 32 of the electrode 30. It is necessaryto also provide a voltage source, not shown, for providing the necessarypotential to the two anodes 124 and 126. A control grid 123 to which theselection signals are applied is associated with the anode 124. Acontrol grid 13% to which selection voltages are applied is associatedwith the anode 126 for controlling the other segment 32 of the electrode33. The amplification of each of these triodes may easily be made tohave a value greater than 50. A more thorough description of theseamplifier structures which are enclosed within the cathode ray tubes isgiven in U.S. Patent 3,065,368, issued November 20, 1962, entitledElectron Device by E. Atti, and assigned to the same assignee.

In the structure shown in FIG. 8, it is found that for a planar typecathode, the cathode image formed on the screen is itself not in aplane. However, it is nearly so, if the diameter of the cathode beingimaged is no more than about of the diameter of the aperture in thecontrol grid. It is found that in such a structure as described that thebeam forming plate 121 can be made slightly concave with respect to thefluorescent screen which will result in throwing almost a perfectly fiatimage up to an object distance from the axis equal to about A2 of thegrid hole radius.

Referring in detail now to the circuit system illustrated in FIG. 8, ithas been previously stated that one of the existing weaknesses ofpresent character producing tubes is the fact that they are unable toform the high intensity electron beam spot of the normal cathode raytube. For several types of applications, it is desirable that such aspot be available. FIG. 8 provides a tube which may produce the usualtype picture under normal operation and which on receipt of a commandpulse changes to a device presenting characters. In this operation, thetube will put down marking symbols which fall on or near the echosignals and thus can identify them. In this application, it is usuallynecessary that the distance between the cathode 64 and the beam formingplate 121 be increased over the conventional operation. Furthermore, itis necessary that the beam forming plate 121 be made of a very open meshconstruction as is indicated in FIG. 10. The purpose of the open meshconstruction is to permit as free a passage as possible to an electronbeam. In the case of the embodiment shown in FIG. 10, about 50 percenttransmis sion is possible.

To convert the tube from a character producing tube to a normal cathoderay tube, it is necessary to provide a switch which is connected to thebeam forming plate 121. The switch 140 provides means of joining thevirtual cathode plate either to the accelerator anode 72 or to the smallpositive potential source 71 of up to about 20 volts. When the beamforming plate 121 is connected to the electrode 72, the tube is intendedto operate as a normal cathode ray tube imaging the crossover formed bythe triode comprising the electrodes 64, 68 and 72. The beam intensitymay now be controlled in the usual manner by variation of the negativepotential on control modulator 68. When the virtual cathode plate 121 isconnected to the source 71, the triode composed of the electrodes 64,

63 and 72 ilhiminates the virtual cathode 121 which is imaged by themain gun comprising electrode 90, 48 and 96. The optics of the gun areso arranged that no change in the potential of the control grid 99 isneeded to focus the beam. This, of course, simplifies the switchingoperation. This is accomplished in this electrode configuration onaccount of the freedom with which the positive potential of theelectrode 72 may be selected. It has been found that variations in thepotential of the source 69 have very little eflect on the virtualcathode imaging conditions. It is thus possible to choose the amount ofvoltage from the source 69 after the tube is set up so that thecross-over formed by the triode structures 64, 63 and 2 2 is focusedwithout change in the potential on the control grid from source 73. Thebrightness of the spot when the device is operated as a normal cathoderay tube is controlled by the potential source 67 applied to themodulator 68. The switch 140 is illustrated as only mechanical but it isof course obvious that it may comprise a thermionic trigger of some sortrequiring only a single pulse to effect the switching operation. When inthe normal cathode ray tube operation position, ail elements of theselector electrode 48 would normally be at the same potential as thefinal anode In order to avoid confusion between an echo and itsidentifying symbol, it might be desirable that this be effected byslightly tilting the portions 64, 68 and 72 of the gun. This will notchange the position of the beam forming plate 121.

In practice, higher character brightness on the fluorescent displayscreen would normaily be achieved by the use of post deflectionacceleration of the shaped electron beam.

While I have shown my invention in only a few forms it will be obviousto those skilled in the art that it is not as limited but is susceptibleof various other changes and limitations without departing from thespirit and scope thereof.

I claim as my invention:

1. A cathode ray display system comprising an electron sensitive target,a beam generating means for supplying and directing a primary beam ofelectrons along a given path, said beam generating means comprising acathode, a control grid having an aperture therein and an acceleratingelectrode, a beam shaping member positioned transverse to the path ofsaid electrons leaving said accelerating electrode, said beam shapingmember comprising a plurality of areas, each of said areas having acharacter shaped aperture provided therein, said areas of said beamshaping electrode positioned to minimize the amount of electron beaminterception, said character shaped apertures providing a plurality ofcharacter shaped electron beams, a first electrode member having adiaphragm and an aperture provided therein and positioned adjacent tosaid beam shaping member for focusing the character shaped electronbeams from said beam shaping electrode to a composite beam crossover, afirst deflection means including a plurality of electrically insulatingmembers encompassing said character shaped electron beams and positionednear said crossover, a second electrode including a diaphragm and havingan aperture provided therein positioned between said first deflectionmeans and said electron sensitive target, the aperture in said diaphragmof said second electrode being adapted to pass a predetermined charactershaped electron beam, said first deflection means provided for directingone of the plurality of character shaped electron beams through theaperture in said diaphragm of said second electrode, a second deflectionmeans positioned between said second electrode and said screen [ordeflecting the character shaped electron beam emerging from saiddiaphragm of said second electrode onto said target in which the objectis the beam shaping member and means associated with said electron gunfor secondly focusing the composite beam on said electron sensitivetarget whereby substantially all of emerging electrons from said beamshaping member are formed into a spot of high electron density on saidelectron sensitive target and in which the object is the composite beamcrossover.

2. A cathode ray tube display system comprising a target member, anelectrode structure for generating an electron beam for scanning saidtarget member, said electrode structure comprising a beam shaping memberhaving a plurality of character shaped apertures therein, a firstelectrode system positioned on the opposite side of said beam shapingmember with respect to said target comprising a cathode, a control gridand an accelerating electrode for generating an electron beam to form afirst cross-over near said control grid and superimposing said electronbeam over the character shaped apertures in said beam shaping member, asecond electrode system positioned on the opposite side of said beamshaping member with respect to said first electrode system, means forestablishing a retarding electric field near said beam shaping member toreduce the velocity of the electrons within the electron beam generatedby said first electrode system within the immediate region of said beamshaping member to form in effect a virtual cathode for said secondelectrode system, said second electrode system comprising a control gridand a selection electrode operating at a voltage to form a secondcrossover near said selection electrode, said selection electrodeincluding a plurality of insulating members encompassing the charactershaped electron beams emerging from said beam shaping member, a firstelectrode member including a diaphragm and having an aperture providedtherein positioned between said selection electrode and said target andmeans for applying a diiference in potential to said insulated membersof said selection electrode to deflect said character shaped electronbeams emerging from said beam shaping member about a common apex locatedat said crossover to selectively allow one of said character shapedbeams to pass through the aperture in said diaphragm of said firstelectrode member to said target in which the object is the beam shapingmember.

3. A cathode ray display system comprising a target member, an electrodestructure for generating an electron beam for scanning said target, saidelectrode structure comprising a beam shaping member having a pluralityof character shaped apertures therein, a first electrode systempositioned on the opposite side of said beam shaping member with respectto said target comprising a cathode, a control grid and an acceleratingelectrode for generating a primary electron beam. to form a firstcrossover near said control grid and superimposing said primary electronbeam over the character shaped apertures within said beam shapingmember, a second electrode system positioned on the opposite side ofsaid beam shaping member with respect to said first electrode system,means for establishing a retarding electric field near said beam shapingmember to reduce the velocity of the electrons emerging from thecharacter shaped apertures in said beam shaping member to form in effecta virtual cathode for said second electrode system, said secondelectrode system comprising a control grid and a selection electrodeoperating at a voltage to form a second crossover near said selectionelectrode, the control grid of said second electrode system comprising adiaphragm having an aperture therein through which the eiectron beamsfrom said beam shaping member pass, said selection electrode of saidsecond electrode system including a plurality of insulated memberspositioned about the character shaped electron beams, an anode memberincluding a diaphragm and provided with an aperture therein positionedbetween said selection electrode and said target and means for applyinga diiierence in potential to said insulated members of said selectionelectrode to deflect said character shaped electron beams about a commonapex located at said second crossover and to selectively allow one ofsaid beams to pass through the aperture in said anode to said target.

4. A cathode ray tube system comprising a target memher, an electrodestructure for generating an electron beam for scanning said targetmember, said electrode structure comprising a beam shaping member havinga plurality of character shaped apertures therein, a first electrodesystem positioned on the opposite side of said beam shaping member withrespect to said target comprising a cathode, said first electrode systemincluding a control grid and an accelerating electrode for generating anelectron beam to form a first crossover near said control grid andsuperimposing said electron beam over the character shaped apertureswithin said beam shaping member, a second electrode system positioned onthe opposite side of said beam shaping member with respect to said firstelectrode system, means for establishing a first potential on said beamshaping member to reduce the velocity of the electrons Within theimmediate region of said beam shaping member to form in eifect a virtualcathode for said second electrode system, said second electrode systemcomprised of a control grid and a selection electrode operating at avoltage to form a second crossover near said selection electrode, saidselection electrode including a plurality of insulated membersencompassing the character shaped electron beams emerging from said beamshaping member, an anode comprising a diaphragm having an aperturetherein, said anode located between said selection electrode and saidtarget, means for applying a difference in potential to said insulatedmembers of said selection electrode to deflect said electron beamsemerging from said beam shaping member to selectively allow one of saidbeams to pass through the aperture in said anode and onto said target toform a character shaped spot in which the object is the beam shapingmember and means for establishing a second potential on said beamshaping member and equal voltages on the insulated members of saidselection electrode to focus said electron beam onto said target to forma spot of high electron density in which the object is the firstcrossover.

5. In a cathode ray tube system comprising a target, a first electrodesystem for generating an electron beam and forming a first crossover ofsaid beam, a beam shaping electrode positioned Within the path of saidbeam having a plurality of character shaped apertures therein and ontowhich said electron beam is directed to produce a plurality of charactershaped electron beams from the opposite side thereof, a second electrodesystem positioned on the opposite side of said beam shaping member withrespect to said first electrode system comprising a control grid havingan aperture therein, a selection electrode comprising a plurality ofinsulated members encompassing the character shaped electron beamsemerging from said beam shaping member and an anode member including adiaphragm having an aperture therein provided between said selectionmeans and said target, the combination comprising means for applying afirst potential to said beam shaping member to focus the electron beamonto said target to obtain a small area spot of high electron density inwhich the object is the electron beam at the first crossover and meansfor applying a second potential to said beam shaping member and of amore negative potential than said first potential so that the velocityof the electrons emerging from said beam shaping member is of a lowvalue such that said beam shaping electrode acts as a virtual cathodefor said second electrode system and said second electrode system formsa second'crossover near said selection electrode and means for applyinga voltage differential between said insulated members of said selectionelectrode to selectively allow one of said character shaped electronbeams to pass through the aperture in said anode and form a charactershaped spot on said target in which the object is the electron beamshaping electrode.

6. A shaped beam tube comprising means for emitting electrons to form anelectron beam, a matrix electrode having a plurality of character shapedapertures positioned in close proximity to said electron emitting means,

said matrix being at a low potential with respect to said electronemitting means, means for causing electrons emitted from said electronemitting means to traverse the character shaped apertures in said matrixand emerger as a plurality of distinguishable character shaped electronbeams, a target member for receiving the electrons emitted from saidelectron emitting means, an electrode focusing means positioned betweensaid matrix and said target for firstly selectively passing one of saidcharacter shaped electron beams to said target member in which theobject is said matrix and then secondly for focusing a substantial partof the electron beam onto said target member in a spot of high electrondensity in which the object is the first crossover of said beam.

7. A cathode ray display system comprising an electron sensitive target,an electron gun structure comprising a beam generating means forsupplying and directing a primary beam of electrons along a given path,a beam shaping member positioned across the path of said primary beam ofelectrons, said beam shaping member operating at a potential such thatthe electrons in said primary beam of electrons are reduced in velocityon arriving in the immediate region of said beam shaping member, saidbeam shaping member having character shaped openings for providing aplurality of character shaped electron beams emerging from said openingson interception of said primary beam, a first electrode memberpositioned adjacent to said beam shaping member on the side of said beamshaping member facing said electron sensitive target for forming anddirecting the character shaped electron beams to a composite beamcrossover, a first deflection means including a plurality ofelectrically insulated members surrounding said character shapedelectron beams and positioned near said crossover, a second electrodeincluding a diaphragm having an aperture therein positioned between saidfirst deflection electrode means and said electron sensitive target, theaperture in said diaphragm being adapted to pass one of said charactershaped electron beams, a first circuit means operatively associated withsaid electron gun structure to direct and focus one of said charactershaped electron beams through said aperture in said diaphragm and ontosaid electron sensitive target in the form of said shaped character inwhich the object is the beam shaping member and a second circuit meansoperatively associated with said electron gun to direct and focus thecomposite beam crossover onto said electron sensitive target wherebysubstantially all of the emerging electrons from said beam shapingmember impinge on said electron sensitive target to provide a spot ofhigh electron density in which the object is said composite crossoverand switching means for selectively applying said first or secondcircuit means to said electron gun.

References Qited by the Examiner UNITED STATES PATENTS 2,283,383 5/42McNaney 315-1 2,761,988 9/56 McNaney 313-86 XR 2,790,103 4/57 McNaney 3151 2,811,668 10/57 McNaney 3151 2,844,759 7/58 Bryan 313-70 2,862,14411/58 McNaney 315-1 2,870,361 1/59 Aiken 315l FOREIGN PATENTS 521,803 540 Great Britain.

OTHER REFERENCES Anthony: New Apparatus and Techniques of Air TrafficControl Data Handling and Display, I.R.E. Convention Record, vol. 3,part 10, 1955.

ROBERT SEGAL, Acting Primary Examiner.

RALPH G. NILSON, ARTHUR GAUSS, Examiners.

6. A SHAPED BEAM TUBE COMPRISING MEANS FOR EMITTING ELECTRONS TO FORM ANELECTRON BEAM, A MATRIX ELECTRODE HAVING A PLURALITY OF CHARACTER SHAPEDAPERTURES POSITIONED IN CLOSE PROXIMITY OF SAID ELECTRON EMITTING MEANS,SAID MATRIX BEING AT A LOW POTENTIAL WITH RESPECT TO SAID ELECTRONEMITTING MEANS, MEANS FOR CAUSING ELECTRONS EMITTED FROM SAID ELECTRONEMITTING MEANS TO TRAVERSE THE CHARACTER SHAPED APERTURES IN SAID MATRIXAND EMERGER AS A PLURALITY OF DISTINGUISHABLE CHARACTER SHAPED ELECTRONBEAMS, A TARGET MEMBER FOR RECEIVING THE ELECTRON EMITTED FROM SAIDELECTRON EMITTING MEANS, AN ELECTRODE FOCUSING MEANS POSITIONED BETWEENSAID MATRIX AND SAID TARGET FOR FIRSTLY SELECTIVELY PASSIN GONE OF SAIDCHARACTER SHAPED ELECTRON BEAMS TO SAID TARGET MEMBER IN WHICH THEOBJECT IS SAID MATRIX AND THEN SECONDLY FOR FOCUSING A SUBSTANTIAL PARTOF THE ELECTRON BEAM ONTO SAID TARGET MEMBER IN A SPOT OF HIGH ELECTRONDENSITY IN WHICH THE OBJECT IS THE FIRST CROSSOVER OF SAID BEAM.